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-rw-r--r--kernel/locking/lock_events.c10
-rw-r--r--kernel/locking/lockdep_proc.c2
-rw-r--r--kernel/locking/locktorture.c214
-rw-r--r--kernel/locking/mutex.c3
-rw-r--r--kernel/locking/osq_lock.c37
-rw-r--r--kernel/locking/rtmutex.c37
-rw-r--r--kernel/locking/rwbase_rt.c8
-rw-r--r--kernel/locking/rwsem.c8
-rw-r--r--kernel/locking/spinlock_rt.c6
-rw-r--r--kernel/locking/test-ww_mutex.c28
-rw-r--r--kernel/locking/ww_rt_mutex.c2
11 files changed, 269 insertions, 86 deletions
diff --git a/kernel/locking/lock_events.c b/kernel/locking/lock_events.c
index fa2c2f951c..e68d820995 100644
--- a/kernel/locking/lock_events.c
+++ b/kernel/locking/lock_events.c
@@ -146,7 +146,7 @@ static int __init init_lockevent_counts(void)
struct dentry *d_counts = debugfs_create_dir(LOCK_EVENTS_DIR, NULL);
int i;
- if (!d_counts)
+ if (IS_ERR(d_counts))
goto out;
/*
@@ -159,14 +159,14 @@ static int __init init_lockevent_counts(void)
for (i = 0; i < lockevent_num; i++) {
if (skip_lockevent(lockevent_names[i]))
continue;
- if (!debugfs_create_file(lockevent_names[i], 0400, d_counts,
- (void *)(long)i, &fops_lockevent))
+ if (IS_ERR(debugfs_create_file(lockevent_names[i], 0400, d_counts,
+ (void *)(long)i, &fops_lockevent)))
goto fail_undo;
}
- if (!debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200,
+ if (IS_ERR(debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200,
d_counts, (void *)(long)LOCKEVENT_reset_cnts,
- &fops_lockevent))
+ &fops_lockevent)))
goto fail_undo;
return 0;
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 15fdc7fa5c..e2bfb1db58 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -440,7 +440,7 @@ static void snprint_time(char *buf, size_t bufsiz, s64 nr)
static void seq_time(struct seq_file *m, s64 time)
{
- char num[15];
+ char num[22];
snprint_time(num, sizeof(num), time);
seq_printf(m, " %14s", num);
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 270c7f80ce..69d3cd2cfc 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -33,21 +33,23 @@
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
-torture_param(int, nwriters_stress, -1, "Number of write-locking stress-test threads");
-torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads");
+torture_param(int, acq_writer_lim, 0, "Write_acquisition time limit (jiffies).");
+torture_param(int, call_rcu_chains, 0, "Self-propagate call_rcu() chains during test (0=disable).");
torture_param(int, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable");
+torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
+torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads");
+torture_param(int, nwriters_stress, -1, "Number of write-locking stress-test threads");
torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
+torture_param(int, rt_boost, 2,
+ "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
+torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
torture_param(int, shuffle_interval, 3, "Number of jiffies between shuffles, 0=disable");
torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
-torture_param(int, rt_boost, 2,
- "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
-torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
-torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority");
torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
-torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
+torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority");
/* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */
#define MAX_NESTED_LOCKS 8
@@ -56,6 +58,55 @@ module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type,
"Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");
+static cpumask_var_t bind_readers; // Bind the readers to the specified set of CPUs.
+static cpumask_var_t bind_writers; // Bind the writers to the specified set of CPUs.
+
+// Parse a cpumask kernel parameter. If there are more users later on,
+// this might need to got to a more central location.
+static int param_set_cpumask(const char *val, const struct kernel_param *kp)
+{
+ cpumask_var_t *cm_bind = kp->arg;
+ int ret;
+ char *s;
+
+ if (!alloc_cpumask_var(cm_bind, GFP_KERNEL)) {
+ s = "Out of memory";
+ ret = -ENOMEM;
+ goto out_err;
+ }
+ ret = cpulist_parse(val, *cm_bind);
+ if (!ret)
+ return ret;
+ s = "Bad CPU range";
+out_err:
+ pr_warn("%s: %s, all CPUs set\n", kp->name, s);
+ cpumask_setall(*cm_bind);
+ return ret;
+}
+
+// Output a cpumask kernel parameter.
+static int param_get_cpumask(char *buffer, const struct kernel_param *kp)
+{
+ cpumask_var_t *cm_bind = kp->arg;
+
+ return sprintf(buffer, "%*pbl", cpumask_pr_args(*cm_bind));
+}
+
+static bool cpumask_nonempty(cpumask_var_t mask)
+{
+ return cpumask_available(mask) && !cpumask_empty(mask);
+}
+
+static const struct kernel_param_ops lt_bind_ops = {
+ .set = param_set_cpumask,
+ .get = param_get_cpumask,
+};
+
+module_param_cb(bind_readers, &lt_bind_ops, &bind_readers, 0644);
+module_param_cb(bind_writers, &lt_bind_ops, &bind_writers, 0644);
+
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
+
static struct task_struct *stats_task;
static struct task_struct **writer_tasks;
static struct task_struct **reader_tasks;
@@ -69,6 +120,12 @@ struct lock_stress_stats {
long n_lock_acquired;
};
+struct call_rcu_chain {
+ struct rcu_head crc_rh;
+ bool crc_stop;
+};
+struct call_rcu_chain *call_rcu_chain;
+
/* Forward reference. */
static void lock_torture_cleanup(void);
@@ -116,12 +173,9 @@ static int torture_lock_busted_write_lock(int tid __maybe_unused)
static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
{
- const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
-
/* We want a long delay occasionally to force massive contention. */
- if (!(torture_random(trsp) %
- (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+ mdelay(long_hold);
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
torture_preempt_schedule(); /* Allow test to be preempted. */
}
@@ -194,15 +248,14 @@ __acquires(torture_spinlock)
static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
{
const unsigned long shortdelay_us = 2;
- const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
unsigned long j;
/* We want a short delay mostly to emulate likely code, and
* we want a long delay occasionally to force massive contention.
*/
- if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * longdelay_ms))) {
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) {
j = jiffies;
- mdelay(longdelay_ms);
+ mdelay(long_hold);
pr_alert("%s: delay = %lu jiffies.\n", __func__, jiffies - j);
}
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 200 * shortdelay_us)))
@@ -320,14 +373,12 @@ __acquires(torture_rwlock)
static void torture_rwlock_write_delay(struct torture_random_state *trsp)
{
const unsigned long shortdelay_us = 2;
- const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
/* We want a short delay mostly to emulate likely code, and
* we want a long delay occasionally to force massive contention.
*/
- if (!(torture_random(trsp) %
- (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+ mdelay(long_hold);
else
udelay(shortdelay_us);
}
@@ -348,14 +399,12 @@ __acquires(torture_rwlock)
static void torture_rwlock_read_delay(struct torture_random_state *trsp)
{
const unsigned long shortdelay_us = 10;
- const unsigned long longdelay_ms = 100;
/* We want a short delay mostly to emulate likely code, and
* we want a long delay occasionally to force massive contention.
*/
- if (!(torture_random(trsp) %
- (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealreaders_stress * 2000 * long_hold)))
+ mdelay(long_hold);
else
udelay(shortdelay_us);
}
@@ -453,12 +502,9 @@ __acquires(torture_mutex)
static void torture_mutex_delay(struct torture_random_state *trsp)
{
- const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
-
/* We want a long delay occasionally to force massive contention. */
- if (!(torture_random(trsp) %
- (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms * 5);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+ mdelay(long_hold * 5);
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
torture_preempt_schedule(); /* Allow test to be preempted. */
}
@@ -626,15 +672,13 @@ __acquires(torture_rtmutex)
static void torture_rtmutex_delay(struct torture_random_state *trsp)
{
const unsigned long shortdelay_us = 2;
- const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
/*
* We want a short delay mostly to emulate likely code, and
* we want a long delay occasionally to force massive contention.
*/
- if (!(torture_random(trsp) %
- (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+ mdelay(long_hold);
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 200 * shortdelay_us)))
udelay(shortdelay_us);
@@ -691,12 +735,9 @@ __acquires(torture_rwsem)
static void torture_rwsem_write_delay(struct torture_random_state *trsp)
{
- const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
-
/* We want a long delay occasionally to force massive contention. */
- if (!(torture_random(trsp) %
- (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms * 10);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+ mdelay(long_hold * 10);
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
torture_preempt_schedule(); /* Allow test to be preempted. */
}
@@ -716,14 +757,11 @@ __acquires(torture_rwsem)
static void torture_rwsem_read_delay(struct torture_random_state *trsp)
{
- const unsigned long longdelay_ms = 100;
-
/* We want a long delay occasionally to force massive contention. */
- if (!(torture_random(trsp) %
- (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
- mdelay(longdelay_ms * 2);
+ if (long_hold && !(torture_random(trsp) % (cxt.nrealreaders_stress * 2000 * long_hold)))
+ mdelay(long_hold * 2);
else
- mdelay(longdelay_ms / 2);
+ mdelay(long_hold / 2);
if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
torture_preempt_schedule(); /* Allow test to be preempted. */
}
@@ -803,11 +841,13 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = {
*/
static int lock_torture_writer(void *arg)
{
+ unsigned long j;
+ unsigned long j1;
+ u32 lockset_mask;
struct lock_stress_stats *lwsp = arg;
- int tid = lwsp - cxt.lwsa;
DEFINE_TORTURE_RANDOM(rand);
- u32 lockset_mask;
bool skip_main_lock;
+ int tid = lwsp - cxt.lwsa;
VERBOSE_TOROUT_STRING("lock_torture_writer task started");
if (!rt_task(current))
@@ -834,17 +874,24 @@ static int lock_torture_writer(void *arg)
cxt.cur_ops->nested_lock(tid, lockset_mask);
if (!skip_main_lock) {
+ if (acq_writer_lim > 0)
+ j = jiffies;
cxt.cur_ops->writelock(tid);
if (WARN_ON_ONCE(lock_is_write_held))
lwsp->n_lock_fail++;
lock_is_write_held = true;
if (WARN_ON_ONCE(atomic_read(&lock_is_read_held)))
lwsp->n_lock_fail++; /* rare, but... */
-
+ if (acq_writer_lim > 0) {
+ j1 = jiffies;
+ WARN_ONCE(time_after(j1, j + acq_writer_lim),
+ "%s: Lock acquisition took %lu jiffies.\n",
+ __func__, j1 - j);
+ }
lwsp->n_lock_acquired++;
- }
- if (!skip_main_lock) {
+
cxt.cur_ops->write_delay(&rand);
+
lock_is_write_held = false;
WRITE_ONCE(last_lock_release, jiffies);
cxt.cur_ops->writeunlock(tid);
@@ -986,16 +1033,69 @@ static int lock_torture_stats(void *arg)
return 0;
}
+
static inline void
lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
const char *tag)
{
+ static cpumask_t cpumask_all;
+ cpumask_t *rcmp = cpumask_nonempty(bind_readers) ? bind_readers : &cpumask_all;
+ cpumask_t *wcmp = cpumask_nonempty(bind_writers) ? bind_writers : &cpumask_all;
+
+ cpumask_setall(&cpumask_all);
pr_alert("%s" TORTURE_FLAG
- "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
+ "--- %s%s: acq_writer_lim=%d bind_readers=%*pbl bind_writers=%*pbl call_rcu_chains=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d\n",
torture_type, tag, cxt.debug_lock ? " [debug]": "",
- cxt.nrealwriters_stress, cxt.nrealreaders_stress,
- nested_locks, stat_interval, verbose, shuffle_interval,
- stutter, shutdown_secs, onoff_interval, onoff_holdoff);
+ acq_writer_lim, cpumask_pr_args(rcmp), cpumask_pr_args(wcmp),
+ call_rcu_chains, long_hold, nested_locks, cxt.nrealreaders_stress,
+ cxt.nrealwriters_stress, onoff_holdoff, onoff_interval, rt_boost,
+ rt_boost_factor, shuffle_interval, shutdown_secs, stat_interval, stutter,
+ verbose, writer_fifo);
+}
+
+// If requested, maintain call_rcu() chains to keep a grace period always
+// in flight. These increase the probability of getting an RCU CPU stall
+// warning and associated diagnostics when a locking primitive stalls.
+
+static void call_rcu_chain_cb(struct rcu_head *rhp)
+{
+ struct call_rcu_chain *crcp = container_of(rhp, struct call_rcu_chain, crc_rh);
+
+ if (!smp_load_acquire(&crcp->crc_stop)) {
+ (void)start_poll_synchronize_rcu(); // Start one grace period...
+ call_rcu(&crcp->crc_rh, call_rcu_chain_cb); // ... and later start another.
+ }
+}
+
+// Start the requested number of call_rcu() chains.
+static int call_rcu_chain_init(void)
+{
+ int i;
+
+ if (call_rcu_chains <= 0)
+ return 0;
+ call_rcu_chain = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain), GFP_KERNEL);
+ if (!call_rcu_chain)
+ return -ENOMEM;
+ for (i = 0; i < call_rcu_chains; i++) {
+ call_rcu_chain[i].crc_stop = false;
+ call_rcu(&call_rcu_chain[i].crc_rh, call_rcu_chain_cb);
+ }
+ return 0;
+}
+
+// Stop all of the call_rcu() chains.
+static void call_rcu_chain_cleanup(void)
+{
+ int i;
+
+ if (!call_rcu_chain)
+ return;
+ for (i = 0; i < call_rcu_chains; i++)
+ smp_store_release(&call_rcu_chain[i].crc_stop, true);
+ rcu_barrier();
+ kfree(call_rcu_chain);
+ call_rcu_chain = NULL;
}
static void lock_torture_cleanup(void)
@@ -1048,6 +1148,8 @@ static void lock_torture_cleanup(void)
kfree(cxt.lrsa);
cxt.lrsa = NULL;
+ call_rcu_chain_cleanup();
+
end:
if (cxt.init_called) {
if (cxt.cur_ops->exit)
@@ -1177,6 +1279,10 @@ static int __init lock_torture_init(void)
}
}
+ firsterr = call_rcu_chain_init();
+ if (torture_init_error(firsterr))
+ goto unwind;
+
lock_torture_print_module_parms(cxt.cur_ops, "Start of test");
/* Prepare torture context. */
@@ -1250,6 +1356,8 @@ static int __init lock_torture_init(void)
writer_fifo ? sched_set_fifo : NULL);
if (torture_init_error(firsterr))
goto unwind;
+ if (cpumask_nonempty(bind_writers))
+ torture_sched_setaffinity(writer_tasks[i]->pid, bind_writers);
create_reader:
if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
@@ -1259,6 +1367,8 @@ static int __init lock_torture_init(void)
reader_tasks[j]);
if (torture_init_error(firsterr))
goto unwind;
+ if (cpumask_nonempty(bind_readers))
+ torture_sched_setaffinity(reader_tasks[j]->pid, bind_readers);
}
if (stat_interval > 0) {
firsterr = torture_create_kthread(lock_torture_stats, NULL,
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index d973fe6041..2deeeca3e7 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -1126,6 +1126,9 @@ EXPORT_SYMBOL(ww_mutex_lock_interruptible);
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
#endif /* !CONFIG_PREEMPT_RT */
+EXPORT_TRACEPOINT_SYMBOL_GPL(contention_begin);
+EXPORT_TRACEPOINT_SYMBOL_GPL(contention_end);
+
/**
* atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
* @cnt: the atomic which we are to dec
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
index d5610ad52b..75a6f61338 100644
--- a/kernel/locking/osq_lock.c
+++ b/kernel/locking/osq_lock.c
@@ -11,6 +11,13 @@
* called from interrupt context and we have preemption disabled while
* spinning.
*/
+
+struct optimistic_spin_node {
+ struct optimistic_spin_node *next, *prev;
+ int locked; /* 1 if lock acquired */
+ int cpu; /* encoded CPU # + 1 value */
+};
+
static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_node);
/*
@@ -37,32 +44,28 @@ static inline struct optimistic_spin_node *decode_cpu(int encoded_cpu_val)
/*
* Get a stable @node->next pointer, either for unlock() or unqueue() purposes.
* Can return NULL in case we were the last queued and we updated @lock instead.
+ *
+ * If osq_lock() is being cancelled there must be a previous node
+ * and 'old_cpu' is its CPU #.
+ * For osq_unlock() there is never a previous node and old_cpu is
+ * set to OSQ_UNLOCKED_VAL.
*/
static inline struct optimistic_spin_node *
osq_wait_next(struct optimistic_spin_queue *lock,
struct optimistic_spin_node *node,
- struct optimistic_spin_node *prev)
+ int old_cpu)
{
- struct optimistic_spin_node *next = NULL;
int curr = encode_cpu(smp_processor_id());
- int old;
-
- /*
- * If there is a prev node in queue, then the 'old' value will be
- * the prev node's CPU #, else it's set to OSQ_UNLOCKED_VAL since if
- * we're currently last in queue, then the queue will then become empty.
- */
- old = prev ? prev->cpu : OSQ_UNLOCKED_VAL;
for (;;) {
if (atomic_read(&lock->tail) == curr &&
- atomic_cmpxchg_acquire(&lock->tail, curr, old) == curr) {
+ atomic_cmpxchg_acquire(&lock->tail, curr, old_cpu) == curr) {
/*
* We were the last queued, we moved @lock back. @prev
* will now observe @lock and will complete its
* unlock()/unqueue().
*/
- break;
+ return NULL;
}
/*
@@ -76,15 +79,15 @@ osq_wait_next(struct optimistic_spin_queue *lock,
* wait for a new @node->next from its Step-C.
*/
if (node->next) {
+ struct optimistic_spin_node *next;
+
next = xchg(&node->next, NULL);
if (next)
- break;
+ return next;
}
cpu_relax();
}
-
- return next;
}
bool osq_lock(struct optimistic_spin_queue *lock)
@@ -186,7 +189,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
* back to @prev.
*/
- next = osq_wait_next(lock, node, prev);
+ next = osq_wait_next(lock, node, prev->cpu);
if (!next)
return false;
@@ -226,7 +229,7 @@ void osq_unlock(struct optimistic_spin_queue *lock)
return;
}
- next = osq_wait_next(lock, node, NULL);
+ next = osq_wait_next(lock, node, OSQ_UNLOCKED_VAL);
if (next)
WRITE_ONCE(next->locked, 1);
}
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 21db0df0eb..4a10e8c16f 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -218,6 +218,11 @@ static __always_inline bool rt_mutex_cmpxchg_acquire(struct rt_mutex_base *lock,
return try_cmpxchg_acquire(&lock->owner, &old, new);
}
+static __always_inline bool rt_mutex_try_acquire(struct rt_mutex_base *lock)
+{
+ return rt_mutex_cmpxchg_acquire(lock, NULL, current);
+}
+
static __always_inline bool rt_mutex_cmpxchg_release(struct rt_mutex_base *lock,
struct task_struct *old,
struct task_struct *new)
@@ -297,6 +302,20 @@ static __always_inline bool rt_mutex_cmpxchg_acquire(struct rt_mutex_base *lock,
}
+static int __sched rt_mutex_slowtrylock(struct rt_mutex_base *lock);
+
+static __always_inline bool rt_mutex_try_acquire(struct rt_mutex_base *lock)
+{
+ /*
+ * With debug enabled rt_mutex_cmpxchg trylock() will always fail.
+ *
+ * Avoid unconditionally taking the slow path by using
+ * rt_mutex_slow_trylock() which is covered by the debug code and can
+ * acquire a non-contended rtmutex.
+ */
+ return rt_mutex_slowtrylock(lock);
+}
+
static __always_inline bool rt_mutex_cmpxchg_release(struct rt_mutex_base *lock,
struct task_struct *old,
struct task_struct *new)
@@ -1613,7 +1632,7 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
raw_spin_unlock_irq(&lock->wait_lock);
if (!owner || !rtmutex_spin_on_owner(lock, waiter, owner))
- schedule();
+ rt_mutex_schedule();
raw_spin_lock_irq(&lock->wait_lock);
set_current_state(state);
@@ -1642,7 +1661,7 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
WARN(1, "rtmutex deadlock detected\n");
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
- schedule();
+ rt_mutex_schedule();
}
}
@@ -1738,6 +1757,15 @@ static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
int ret;
/*
+ * Do all pre-schedule work here, before we queue a waiter and invoke
+ * PI -- any such work that trips on rtlock (PREEMPT_RT spinlock) would
+ * otherwise recurse back into task_blocks_on_rt_mutex() through
+ * rtlock_slowlock() and will then enqueue a second waiter for this
+ * same task and things get really confusing real fast.
+ */
+ rt_mutex_pre_schedule();
+
+ /*
* Technically we could use raw_spin_[un]lock_irq() here, but this can
* be called in early boot if the cmpxchg() fast path is disabled
* (debug, no architecture support). In this case we will acquire the
@@ -1748,6 +1776,7 @@ static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
raw_spin_lock_irqsave(&lock->wait_lock, flags);
ret = __rt_mutex_slowlock_locked(lock, ww_ctx, state);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+ rt_mutex_post_schedule();
return ret;
}
@@ -1755,7 +1784,9 @@ static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
unsigned int state)
{
- if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
+ lockdep_assert(!current->pi_blocked_on);
+
+ if (likely(rt_mutex_try_acquire(lock)))
return 0;
return rt_mutex_slowlock(lock, NULL, state);
diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c
index 25ec023947..34a59569db 100644
--- a/kernel/locking/rwbase_rt.c
+++ b/kernel/locking/rwbase_rt.c
@@ -71,6 +71,7 @@ static int __sched __rwbase_read_lock(struct rwbase_rt *rwb,
struct rt_mutex_base *rtm = &rwb->rtmutex;
int ret;
+ rwbase_pre_schedule();
raw_spin_lock_irq(&rtm->wait_lock);
/*
@@ -125,12 +126,15 @@ static int __sched __rwbase_read_lock(struct rwbase_rt *rwb,
rwbase_rtmutex_unlock(rtm);
trace_contention_end(rwb, ret);
+ rwbase_post_schedule();
return ret;
}
static __always_inline int rwbase_read_lock(struct rwbase_rt *rwb,
unsigned int state)
{
+ lockdep_assert(!current->pi_blocked_on);
+
if (rwbase_read_trylock(rwb))
return 0;
@@ -237,6 +241,8 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
/* Force readers into slow path */
atomic_sub(READER_BIAS, &rwb->readers);
+ rwbase_pre_schedule();
+
raw_spin_lock_irqsave(&rtm->wait_lock, flags);
if (__rwbase_write_trylock(rwb))
goto out_unlock;
@@ -248,6 +254,7 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
if (rwbase_signal_pending_state(state, current)) {
rwbase_restore_current_state();
__rwbase_write_unlock(rwb, 0, flags);
+ rwbase_post_schedule();
trace_contention_end(rwb, -EINTR);
return -EINTR;
}
@@ -266,6 +273,7 @@ static int __sched rwbase_write_lock(struct rwbase_rt *rwb,
out_unlock:
raw_spin_unlock_irqrestore(&rtm->wait_lock, flags);
+ rwbase_post_schedule();
return 0;
}
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 9eabd585ce..2340b6d90e 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1427,8 +1427,14 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
#define rwbase_signal_pending_state(state, current) \
signal_pending_state(state, current)
+#define rwbase_pre_schedule() \
+ rt_mutex_pre_schedule()
+
#define rwbase_schedule() \
- schedule()
+ rt_mutex_schedule()
+
+#define rwbase_post_schedule() \
+ rt_mutex_post_schedule()
#include "rwbase_rt.c"
diff --git a/kernel/locking/spinlock_rt.c b/kernel/locking/spinlock_rt.c
index 48a19ed848..38e292454f 100644
--- a/kernel/locking/spinlock_rt.c
+++ b/kernel/locking/spinlock_rt.c
@@ -37,6 +37,8 @@
static __always_inline void rtlock_lock(struct rt_mutex_base *rtm)
{
+ lockdep_assert(!current->pi_blocked_on);
+
if (unlikely(!rt_mutex_cmpxchg_acquire(rtm, NULL, current)))
rtlock_slowlock(rtm);
}
@@ -184,9 +186,13 @@ static __always_inline int rwbase_rtmutex_trylock(struct rt_mutex_base *rtm)
#define rwbase_signal_pending_state(state, current) (0)
+#define rwbase_pre_schedule()
+
#define rwbase_schedule() \
schedule_rtlock()
+#define rwbase_post_schedule()
+
#include "rwbase_rt.c"
/*
* The common functions which get wrapped into the rwlock API.
diff --git a/kernel/locking/test-ww_mutex.c b/kernel/locking/test-ww_mutex.c
index 7c5a8f0549..78719e1ef1 100644
--- a/kernel/locking/test-ww_mutex.c
+++ b/kernel/locking/test-ww_mutex.c
@@ -9,7 +9,7 @@
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/module.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
#include <linux/slab.h>
#include <linux/ww_mutex.h>
@@ -386,6 +386,19 @@ struct stress {
int nlocks;
};
+struct rnd_state rng;
+DEFINE_SPINLOCK(rng_lock);
+
+static inline u32 prandom_u32_below(u32 ceil)
+{
+ u32 ret;
+
+ spin_lock(&rng_lock);
+ ret = prandom_u32_state(&rng) % ceil;
+ spin_unlock(&rng_lock);
+ return ret;
+}
+
static int *get_random_order(int count)
{
int *order;
@@ -399,7 +412,7 @@ static int *get_random_order(int count)
order[n] = n;
for (n = count - 1; n > 1; n--) {
- r = get_random_u32_below(n + 1);
+ r = prandom_u32_below(n + 1);
if (r != n) {
tmp = order[n];
order[n] = order[r];
@@ -452,17 +465,18 @@ retry:
ww_mutex_unlock(&locks[order[n]]);
if (err == -EDEADLK) {
- ww_mutex_lock_slow(&locks[order[contended]], &ctx);
- goto retry;
+ if (!time_after(jiffies, stress->timeout)) {
+ ww_mutex_lock_slow(&locks[order[contended]], &ctx);
+ goto retry;
+ }
}
+ ww_acquire_fini(&ctx);
if (err) {
pr_err_once("stress (%s) failed with %d\n",
__func__, err);
break;
}
-
- ww_acquire_fini(&ctx);
} while (!time_after(jiffies, stress->timeout));
kfree(order);
@@ -629,6 +643,8 @@ static int __init test_ww_mutex_init(void)
printk(KERN_INFO "Beginning ww mutex selftests\n");
+ prandom_seed_state(&rng, get_random_u64());
+
wq = alloc_workqueue("test-ww_mutex", WQ_UNBOUND, 0);
if (!wq)
return -ENOMEM;
diff --git a/kernel/locking/ww_rt_mutex.c b/kernel/locking/ww_rt_mutex.c
index d1473c6241..c7196de838 100644
--- a/kernel/locking/ww_rt_mutex.c
+++ b/kernel/locking/ww_rt_mutex.c
@@ -62,7 +62,7 @@ __ww_rt_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx,
}
mutex_acquire_nest(&rtm->dep_map, 0, 0, nest_lock, ip);
- if (likely(rt_mutex_cmpxchg_acquire(&rtm->rtmutex, NULL, current))) {
+ if (likely(rt_mutex_try_acquire(&rtm->rtmutex))) {
if (ww_ctx)
ww_mutex_set_context_fastpath(lock, ww_ctx);
return 0;